Guides: xpub, read-only API keys, the funding rate, average cost, MiCA and DAC8

• Your xpub and your privacyAn xpub lets anyone find every address of a Bitcoin account, and so its whole history, without being able to spend. What it reveals, its risk, and who to give it to.
• Read-only API keysA read-only API key lets an app see your account without being able to trade or withdraw. The exact permissions on Kraken, Kraken Futures, Coinbase and OKX, and IP restrictions.
• The funding rate explainedThe funding rate is the payment between longs and shorts that keeps a perpetual close to the spot price. Its formula on Binance and Hyperliquid, its caps and what it costs.
• Average cost, FIFO and France's methodAverage cost is one way to count what a crypto you sell cost you; FIFO is another, and each tax authority has its own. The methods, one example worked out, and the rules of France, the UK and the US.
• MiCA and DAC8Since July 2026, MiCA has reserved crypto-asset services for authorised providers, and DAC8 has your 2026 transactions reported to the tax authorities. The dates, what is reported, and how to check a platform.

Each guide opens with a definition, gives the figures that matter and cites its sources: Bitcoin's standards, the platforms' own documentation, tax texts and European texts. It is dated and updated when those sources change.

How these guides are written

• Primary sources: Bitcoin's BIPs, the help pages and documentation of Kraken, Coinbase, OKX, Binance and Hyperliquid, the texts of the tax authorities of France, the United Kingdom and the United States, and those of ESMA, the AMF and the European Commission, read on 27 October 2026 and listed under each guide.
• Figures you can check: every formula and every limit comes from the source cited, with a worked example.
• CentraFIN kept apart: what CentraFIN does is told in a section at the end, with a link to its integration.
• No advice: these guides explain; they recommend no investment.
• Corrected when needed: found a mistake? Write to us: it is fixed as soon as it is confirmed, as our editorial policy sets out.